title: Strong selection genome-wide enhances fitness trade-offs across environments and episodes of selection.
abstract: Fitness trade-offs across episodes of selection and environments influence life-history evolution and adaptive population divergence. Documenting these trade-offs remains challenging as selection can vary in magnitude and direction through time and space. Here, we evaluate fitness trade-offs at the levels of the whole organism and the quantitative trait locus (QTL) in a multiyear field study of Boechera stricta (Brassicaceae), a genetically tractable mustard native to the Rocky Mountains. Reciprocal local adaptation was pronounced for viability, but not for reproductive components of fitness. Instead, local genomes had a fecundity advantage only in the high latitude garden. By estimating realized selection coefficients from individual-level data on viability and reproductive success and permuting the data to infer significance, we examined the genetic basis of fitness trade-offs. This analytical approach (Conditional Neutrality-Antagonistic Pleiotropy, CNAP) identified genetic trade-offs at a flowering phenology QTL (costs of adaptation) and revealed genetic trade-offs across fitness components (costs of reproduction). These patterns would not have emerged from traditional ANOVA-based QTL mapping. Our analytical framework can be applied to other systems to investigate fitness trade-offs. This task is becoming increasingly important as climate change may alter fitness landscapes, potentially disrupting fitness trade-offs that took many generations to evolve.
authors.affiliation: Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, 29208. jtanders@mailbox.sc.edu.
authors.forename: Jill T
authors.initials: JT
authors.lastname: Anderson
authors.forename: Cheng-Ruei
authors.initials: CR
authors.lastname: Lee
authors.forename: Thomas
authors.initials: T
authors.lastname: Mitchell-Olds
mesh_terms: D019607:Brassicaceae / Q000235:genetics*; D004777:Environment; D019143:Evolution, Molecular; D056084:Genetic Fitness; D018745:Genome, Plant; D008957:Models, Genetic; D040641:Quantitative Trait Loci; D012641:Selection, Genetic
keywords: Antagonistic pleiotropy; conditional neutrality; ecological genetics; evolutionary constraints; fitness components; local adaptation